12-24% Rending on Enemy Weak Spot Hit for 3.5s. Stacks 5 times.
Up to 5-20% Strength based on the charge time of your heavy attacks. Stacks 3 times.
5-8% Strength for every 10% of magazine spent during continuous fire. Stacks 5 times.
Gain between 3.5-5% and 14-20% Critical Chance based on current level of peril.
This build also works in non-havok game modes, but is a bit boring and safe in my opinion. I would much rather take a gaze build or venting shriek for higher damage output and more engaging game play. Along with almost any other staff/gun. This build was a core build in the pre-changed havok due to the overbearing nature of shooters. With nerfs to said shooters, you can now get along without it fairly easily, but it can still be nice to have. It is just as safe as it was before. It is also a good build for people who prefer a more supportive play style. For large hordes and in choke points, Flame Staff has infinite cleave, so is extremely useful in those scenarios.
Feel free to swap out Bubble for either walls or venting shriek. Walls are better on some maps with strong points. Walls can be absolutely brutal to waves of specials, particularly muties. Feel free to take venting shriek if your team already has a bubble. Remember to use venting after building up to 16 stacks of soulblaze, because venting shriek bypasses the staff limit and stack damage is exponential, so has significantly more value per stack the more stacks you have. Perilous Combustion also gets you above the 16 stack limit of flame staff as well, so remember that when I suggest that you could drop it for something else (probably not worth it).
They changed Empyric Shock this patch to work with flame staff. Which might offset the nerf to quell canceling primary fire. It is two points, one of which is useless. I haven't decided it if is worth it. If you don't want it, there are several options. Empathic Evasion, Soulstealer, and Kinetic Deflection I think are the best. Kinetic Deflection is much better with venting shriek. Kinetic Deflection is good with venting shriek, because sometimes you get overwhelmed. When this happens, you can just block until max peril, then shriek to get out of the situation.
This build is mostly crowd control and providing bubble for teammates. It has bad boss damage. Flames do decent damage over time, but you are not a boss killer. Try to keep stacks on the boss, but mostly focus on everything else. Remember that primary fire on staff has much more stagger than secondary fire. Use primary when you need to keep hordes (particular ragers) at bay. Use secondary fire to quickly build up stacks and against weaker mixed hordes. Primary fire will keep elites stuck in a chock point for your team to easily pick apart. Uncanny Stike does work with flame stuff, so against hordes with crushers in them, it is useful to swap to dueling sword (or knife), quickly build of stacks of uncanny, swap back to flame staff. Ideally the cycle goes: build up flame stacks -> swap to melee and build up uncanny stacks -> swap back to flame stack to keep flame stacks up -> repeat as necessarily. This is only worth it against groups of crushers, because you give up your blaze away stacks to build up uncanny stacks. For this rotation, do not use heavy points, the point is not for the melee weapon to do damage, but to as quickly as possible build up uncanny stacks. If it is a single crusher, just melee it with heavy attack -> special repeat (dueling sword). This rotation is also much better than penetrating flames.
Empathic Evasion would be nice to have. You could get rid of the 5% crit point, Battle Meditation, or Perilous Combustion, for it and some extra safety vs surprise gunners or just unexpected mobs of normal shooters.
You could also take soul stealer over battle meditation for some additional toughness regen. The reason I take battle meditation is dumb. For the few times that I do blow myself up on accident (it happens to everyone occasionally), I have had battle meditation save me. It is also nice to sometimes have a burst of toughness regen with Quietude and to keep primary fire going for even longer (not that you will really need it).
Brainburst is to help with ranged when you have nothing else to do. Or to remove an annoying special that no one else is able to (sniper or bomber usually). Smite is entirely pointless with this build. Flame Staff does everything smite does, but mostly better (it doesn't stagger crushers). Assail is not an option for the best builds, because you cannot get Psykinetic Aura, which is the best talent point in the game (including every other class), even with the nerf. Assail is fun and can definitely be used to great effect, but it is not in the running for strongest builds.
Finally, this build might exist on the site already. There are not many good builds and there are specific min/max talent point allocations, so you start to see everyone's builds converge. This was for me and to send to friends if they were curious to what I was doing/running.